IV Infusion Rate Calculator
Calculate mL/hr and Drops Per Minute (gtt/min)
10 gtt/mL (Macrodrip)
15 gtt/mL (Macrodrip)
20 gtt/mL (Macrodrip)
60 gtt/mL (Microdrip)
Check your IV tubing package for this value.
Flow Rate (Volumetric):
0 mL/hr
Drip Rate (Gravity):
0 gtt/min
Total Time in Minutes:
0 min
How to Calculate IV Infusion Rates
Accurate calculation of intravenous (IV) infusion rates is a critical nursing skill necessary to ensure patient safety. Whether you are using an electronic infusion pump or calculating drip rates for gravity infusion, understanding the underlying math is essential for preventing medication errors.
The Core Variables
To calculate the rate, you need three specific pieces of information:
- Total Volume (mL): The amount of fluid or medication to be administered.
- Time Duration: How long the infusion should take to complete (usually in hours or minutes).
- Drop Factor (gtt/mL): The calibration of the IV tubing used. This indicates how many drops (gtt) it takes to equal 1 milliliter (mL). This is found on the packaging of the IV tubing.
Standard Tubing Drop Factors
- Macrodrip sets: Common for routine adult fluid replacement. Standard sizes are 10, 15, or 20 gtt/mL.
- Microdrip sets: Used for pediatrics or precise medication administration. Standard size is 60 gtt/mL.
Formulas
1. Calculating mL per Hour (for Infusion Pumps)
If you are setting an electronic pump, you generally need the rate in milliliters per hour.
Rate (mL/hr) = Total Volume (mL) ÷ Time (hr)
2. Calculating Drops per Minute (for Gravity Flow)
If you are manually regulating the clamp on the IV tubing, you need to count the drops per minute.
Drops per Minute (gtt/min) = (Total Volume (mL) × Drop Factor (gtt/mL)) ÷ Total Time (min)
Calculation Example
Scenario: A doctor orders 1,000 mL of Normal Saline to be infused over 8 hours. The IV tubing available has a drop factor of 15 gtt/mL.
Step 1: Calculate mL/hr
1000 mL ÷ 8 hr = 125 mL/hr
Step 2: Calculate gtt/min
First, convert hours to minutes: 8 hours × 60 = 480 minutes.
Then apply the formula:
(1000 mL × 15 gtt/mL) ÷ 480 min
= 15,000 ÷ 480
= 31.25 gtt/min
Since you cannot count a fraction of a drop, you would round to the nearest whole number: 31 gtt/min.
Medical Disclaimer: This calculator is intended for educational and verification purposes only. It should not replace professional clinical judgment or institutional protocols. Always double-check calculations before administering medication or fluids.
function calculateIVRate() {
// Get input values
var totalVolume = parseFloat(document.getElementById('totalVolume').value);
var timeHours = parseFloat(document.getElementById('timeHours').value);
var timeMinutes = parseFloat(document.getElementById('timeMinutes').value);
var dropFactor = parseFloat(document.getElementById('dropFactor').value);
var errorDiv = document.getElementById('error-message');
var resultsArea = document.getElementById('results-area');
// Reset error display
errorDiv.style.display = 'none';
errorDiv.innerText = ";
// Validation logic
if (isNaN(totalVolume) || totalVolume <= 0) {
errorDiv.innerText = "Please enter a valid Total Volume greater than 0.";
errorDiv.style.display = 'block';
resultsArea.style.display = 'none';
return;
}
// Handle empty time inputs
if (isNaN(timeHours)) timeHours = 0;
if (isNaN(timeMinutes)) timeMinutes = 0;
// Calculate total time in minutes and hours
var totalTimeMinutes = (timeHours * 60) + timeMinutes;
var totalTimeHours = totalTimeMinutes / 60;
if (totalTimeMinutes <= 0) {
errorDiv.innerText = "Please enter a valid duration greater than 0.";
errorDiv.style.display = 'block';
resultsArea.style.display = 'none';
return;
}
// — MAIN CALCULATIONS —
// 1. Calculate mL per Hour
var mlPerHour = totalVolume / totalTimeHours;
// 2. Calculate Drops per Minute (gtt/min)
// Formula: (Volume (mL) * Drop Factor (gtt/mL)) / Time (min)
var dropsPerMinute = (totalVolume * dropFactor) / totalTimeMinutes;
// Display Results
// Round mL/hr to 1 decimal place
document.getElementById('resultMlHr').innerHTML = mlPerHour.toFixed(1) + ' mL/hr';
// Round gtt/min to nearest whole number (since you can't count partial drops)
document.getElementById('resultGttMin').innerHTML = Math.round(dropsPerMinute) + ' gtt/min';
document.getElementById('resultTotalMin').innerHTML = totalTimeMinutes + ' min';
resultsArea.style.display = 'block';
}
function resetCalculator() {
document.getElementById('totalVolume').value = ";
document.getElementById('timeHours').value = ";
document.getElementById('timeMinutes').value = '0';
document.getElementById('dropFactor').value = '15';
document.getElementById('results-area').style.display = 'none';
document.getElementById('error-message').style.display = 'none';
}